Carbohydrates and Diabetes Flashcards
Define Monosaccharide, giving 3 examples and where they are found.
Simple sugar.
Glucose - fruit, veg, honey
Fructose - fruits, manufactured food
Galatactose - digestion of lactose
Define Disaccharide, giving 3 Examples and where they are found.
2 simple sugars linked by glycosidic bond between anomeric hydroxyl of cyclic sugar and hydroxyl of second sugar.
Maltose - malt wheat, barley, beer
Sucrose - most common - table sugar, sugar cane, sweet root veg
Lactose - milk
Define Oligosaccharide.
Chain of 3+ monosaccharides linked by glycosidic bonds
Define Polysaccharide and state the predominant mono. and provide other examples
Multiple sugars linked by glycosidic bonds.
D-Glucose
starch, glycogen and cellulose
Starch is a Polysaccharide. State where it is Found and the Two Types of Starch.
Plant cells
unbranched = amylose α-1,6-D
branches = amylopectin α-1-4-D
Glycogen is a Polysaccharide. State where it is Found and Explain the Features of its Structure.
found as a stored carbohydrate in animals
Highly Branched
- surface area for breakdown
Compact from polymer chain coiling
- allows large amount of energy storage
Glycosidic bonds between single chains = a-1,4 link
Where are Carbohydrates Generally Found?
in breads, milk, bean, corn
How are Carbohydrates Formed? (think organically)
Photosynthesis
Provide the 2 Types of Photosynthesis.
Light Dependent
light energy+water ➵ oxygen+ATP+NADPH
Light Independent - Calvin cyle
CO2+ATP+NADPH➵glucose+ADP+Pi+H20+NAP
What are the Functions of Carbs? (5)
- energy storage
- energy production
- build macromolecules - DNA, ATP
- assist in lipid metabolism
- biosynthesis of amino acids
How is Starch Released, and in which pH?
By serous acini in pH 6.7
Give 3 Enzymes used to break down the Main 3 Disaccharides.
Maltase
Sucrase
Lactase
How is more Glucose made, if not from Food?
gluconeogenesis
- glycerol is broken down into glucose
What are the Daily Requirements for Carbs?
2-5 = 15grams
5-11 = 20grams
11-16= 25grams
16-18 = 30grams
Why Can’t Cellulose be Digested?
enzymes can’t hydrolyse the β-1 bonds
3 Places Where Carbohydrates are Digested.
in the oral cavity
in the stomach
in the gastro-intestinal tract of the small intestine
Explain the Two Types of Digestion in the Oral Cavity and the end result?
Mechanical - by parotid and submandibular gland
Chemical - enzymatic
- salivary α-amylase
end result = broken down into monosaccharides
Explain How Salivary α-Amylase is Secreted in the Oral Cavity, the pH it Works at and the Function.
- by serous acini of parotid and submandibular gland
- optimum pH = 6.7
- it hydrolyses α-1,4-linkage from oligo into poly
- works for 1-2 hrs in the stomach before deactivation by gastric acids
State the 2 Enzymes found in the GIT.
- pancreatic amylase
- brush border enzymes
What is Pancreatic Amylase Secreted by? Where is it Secreted? What is the Optimum pH and Function?
- secreted by pancreatic exocrine acini into duodenum through pancreatic duct
- pH = 6.7-7
- hydrolyse α-1,4-linkage and digests more complex carbohydrates
What is the Function of Microvilli in the Small Intestine?
to increase SA, facilitating absorption
How is Galactose and Glucose Absorbed? (4)
for jokes rememberance: The G is SOOO big how can it get through, there
- from intestinal lumen, enters epithelial cell via apical border
- uses active transport and sodium dependent co-transporters (SGLT1)
- leaves epithelial cell via basolateral side
- facilitated diffusion and glucose-cotransporter 2 (GLUT2)
= into blood circulation
How is Fructose Absorbed?
For jokes: F looks like a 5
- from intestinal lumen, enters epithelial cell with GLUT-5
- binds and changes shape
- Leave cell - facilitated diffusion and GLUT-2
= into blood circulation
What Problems are there With Monosaccharides being Absorbed?
the shape makes them polar
= unable to cross the liquid bilayer
solution - need transporter enzymes
What Factors Affect the Rate of Monosaccharide Absorption?
slowed down if:
- mucosa has inflammation or injury
increased if:
- thyroid hormones are active
- mineralocortoids present e.g. aldosterone
- higher sodium concentration - Na/K pump
What is Glucagon, Where is it Made, Where it is Stored and its Function.
Hormone secreted by the α cells in the Islets of Langerhans in the pancreas
stored in the muscles and liver
function = glycogenolysis
- to convert glycogen into glucose.
- adrenaline also promotes breakdown
What is Glycogenolysis?
the breakdown of stored glycogen in the liver into glucose by glucagon to release into the blood stream when blood glucose is low
What is Insulin, Where is it Made, How is it Made (7) and the Function.
A hormone secreted by the β cells in the Islets of Langerhans in the pancreas
How?
- translated by RNA - propreinsulin
- formed in the RER
- packaged into proinsulin - 3 peptide chains
= A chain, B chain and C chain
- proinsulin moves to transgolgi apparatus
- loses C chain, released into blood
- A and B join by disulphide bond
- insulin exits via exocytosis
function = glycogenesis
- glucose into glycogen
What is Glycogenesis?
the stimulation of GLUT 4 to uptake glucose into glycogen by insulin when blood sugar levels are high
What is Insulin Resistance?
When receptors aren’t receptive to insulin present in the body
What is GLUT 4 and its Relevance to Diabetes.
an insulin regulated transporter responsible for glucose uptake
- forms hypoglycaemic drugs in Diabetes Type II
- phosphorylate GLUT4 to make it more available and lowering sensitivity to insulin
What Happens when there is a Deficiency of Insulin?
leads to extracellular hyperglycaemia, intracellular hypoglycaemia and diabetes mellitus
What are the Normal BG Levels?
Fasting = 80-90mg/100ml
After a Meal = 120-140mg/100ml
What is Diabetes Type I and Type II?
Type I = insulin deficiency
- the pancreas doesn’t make insulin as the immune system attacks the Islet cells
Type II = insulin resistance
- pancreas produces more insulin to uptake blood sugar but overtime cells stop responding to insulin, pancreas stops making insulin
State Symptoms of Diabetes (8) PKFVWWXY
- pee more with more glucose in the urine
- higher loss of ketones - fat breakdown
- fatigue
- blurred vision
- impaired wound healing
- unusual weight loss or gain
- dry mouth - cells are dehydrated due to hyperosmotic plasma, can lead to hyperglycaemic coma
- yeast infections
if something hyper - its high, so where must it all be? not in the cell
What are the Macrovascular Complications of Diabetes?
large vessels that are damaged by hyperglycaemia
brain - cerebrovascular diseases, stroke, transient ischaemia, cognitive impairment
heart - corny syndrome, heart attack, congestive heart failure
extremities - diabetic foot, skin ulcer, amputation
What are Microvascular Complications of Diabetes? eye, kidney, nerves
Eye - retinopathy, cataracts, glaucoma
Kidney - nephropathy, microalbuminuria, renal failure
Nerves - neuropathy
Relevance of Diabetes to Dentistry (5)
- dry mouth - caries, no saliva
- gum and periodontal disease
- loss of teeth
- impaired and delayed healing
- infections
What can you do as a Dental Professional (6)
OHI
regular check ups
antibiotics
control blood levels before surgery
mouth wash
if required - artificial saliva
What is the Only Energy Substrate for the Brain?
Glucose
What is the mass of one molcules of Glycogen?
10^8 Daltons
Which 2 Hormones Promote Breakdown?
Glucagon and Adrenaline in the liver
Adrenaline in the muscles
The Role of Glycogen Phosphorylase
activates to increases the levels of glucagon and adrenaline in the blood
stops cleaving when it gets within 4 units of a branch point
What other Enzymes are Required when Glycogen Phosphorylase reaches a Branch Point?
transferase enzyme
- transfers 3 glucose units from one end to the other end of the chain
amylo-a-1,6-glucosidase
- hydroylses the single glucose unit left behind
what is the reaction involving the breakdown of glycogen?
GLYCOGENOLYSIS
glycogen + pi = glucose-1-phosphate + glycogen
by glycogen phosphorylase
G1P:glucose ratio = 8:1
How do the Hormone Signals Work?
- adrenaline and glucagon receptors on the cystol
- activated
- activate adenylate cyclase
- catalysed ATP into cAMP
= amplification cascade
Give 5 Types of Glycogen Storage Diseases FMVAP
Andersen Disease - 1,4-a-glucan glucosidase
- affects liver
= death in 3 years
Forbes’ Disease - amyloid-1,6-glucosidase
- affects liver, muscle, heart
= good prognosis
Pompe’s Disease - lysosomal a-glucosidase
- affects liver, muscle, heart
= death in first 6 months
McArdle Disease - phosphorylase
- affects muscle
= normal lifestyle, must avoid exercise
Von Glerke’s Disease - glucose-6-phosphatase
- affects liver, intestine, kidney
= if survive hypoglycaemia, prognosis is good, hyperuricaemia is a later complication
Define Glycogenesis
glycogen synthesis
How do you Obtain Branching Point on Glucagon?
transfer min 6 alpha-1,4-glucose units onto the chain by introducing a a-1,6 linkage
Use CBE branching enzyme
What if you have a Deficiency of the Branching Enzyme?
leads to Anderson’s Disease
= liver failure and death in first year of life
How Does Insulin Work?
insulin receptors on the cystol activate
- activate protein kinase
Insulin in the Muscles
- increases no. of membrane glucose transporters
- activate glycogen synthesis
Insulin in the Liver
doesn’t affect the number of membrane glucose transporters
- activates glycogen synthesis
How much Glycogen can be Stored?
300g
- after, glucose entering liver is converted to fat and sent to adipose
Define Gluconeogenesis
the synthesis of new glucose made from noncarbohydrate sources in the liver using the precursors lactate, glycerol and amino acids
How much energy does Gluconeogenesis use?
4ATP
2GTP
2NADH
-16kJ/mol
